From the end of the first level onwards, you have the ability to edit your deck. A deck strategy is less necessary early on, but slowly becomes vital as you progress and as you collect more powerful cards.
Landscape cards are the basis of a deck. There are many combinations of landscape cards to fit a role your deck needs to play.
Below are some effective landscape card builds:

Useless Swamp, Useless Swamp, Useless Swamp, Useless Swamp

A Useless Swamp deck is arguably the best or second best faction in the game due to Useless swamp being the faction that has the largest amount of cards that can deal massive amounts of damage (more than enough to fill an entire deck alone) and also have incredibly useful floops that can be powerful enough to single handedly take down the bulkiest of enemies or clear entire battlefields. This deck is the best deck to have for any end game player that has access to most of the cards in the game (most importantly gold).

Cornfields, Cornfields, Cornfields, Cornfields

A Cornfields deck is all about faction synergy. All the cards help each other out to create a very scary force. Not to mention Cornfields has some of the best offensive and defensive cards in the game. Cornfields decks are very well balanced too. This deck is recommended to experienced players who truly know how to get the cards to play off of each other which is crucial to the deck's ability to win matches.

Sandylands, Sandylands, Sandylands, Sandylands

A Sandy Lands deck is just as good as useless swamp it has great offensive cards and just as good defensive card it is highly recommended for people who want to sweep the opponent.

Blue Plains, Blue Plains, Blue Plains, Blue Plains

Pure Blue Plains deck is honestly not that good for begineers or fast players. But if someone wants to play they can. To be able to do well one will have to make use of all the strange floops the creatures have and also of the most powerful of the cards like Camera Dude, Timmy Magic Eyes, Psionic Architect, Ancient Scholar, Woadic Chief, Struzann Jinn, Woadic Marauder... etc You can build this deck around the Camera Dude with falling stars. Doing this thing also provides to lock your opponent. Well that is common way to lock your opponent but that isn't the only way. If you don't have Camera Dude you can use Psionic Architects with Door of Stregth combo. It works well with this deck. Use Door and bring back to hand with Psionic Architect's floop. It works slowly but guarantee victory.

Nicelands, Nicelands, Nicelands, Nicelands

Nice Lands cards are best used in decks with multiple factions (more so than any other faction due to their healing focused style), but a Nice Lands only deck can still be powerful. With the massive healing it can be quite the annoyance to take down for many, not to mention Nice Lands decks still have a few cards that can deal damage (although not as many as the other factions).

Rainbow Stall Deck: (Any 4 different landscapes of choice)

Many players use 3 to 4 different landscapes during the early game due to a lack of cards however during the later game the better players and opponents use 2 different landscapes. This deck is not as good but is moderately easy to use and very amusing to watch. The deck focuses around using creatures who have floop abilities the work better when 4 different landscapes are in play and rainbow creatures, and it also involves lots of spell cards. The aim of the deck is to use several copies of magic gaining cards such as Witch Way, ZaZo's Magic Seeds, and Corn Parthenon to gain a larger field advantage over the opponent but a smaller hand. The deck is better for experienced players who can defend their creatures.

Rainbow Turbo Deck: (Any 4 different landscapes of choice)

This deck is based around using small amount of strong cards and Witch way + Crystal ball synergy (18-24 cards in total). The minimal requirements is: a High level Hero card, 4 Witch Ways, 4 Crystal Balls and 4 5 star creatures of different landscapes. Optional: Up to four Brief Powers, up to 4 Falling Stars and golden low leveled cards.

There is a large chance to have Witch Way or Crystal Ball in hand from the start (and each time you use Crystal Ball), it means that you have immense rushdown potential and in the best case scenario you can reshuffle your hand several times leaving your opponent defenceless against several high level cards and end game on 2nd turn. In the worst case scenario you can lose up to 2 turns and still have same potential later.

Cornfields, Nicelands, Nicelands, Cornfields

A fairly popular choice of deck type giving a balance of attack based and heal based creatures. This deck is weak with cards 1 or 2. To make this deck to the top, you need to have high attack and defence cards. The biggest threat to this deck is that most corn cards are very vulnerable to cerebral blood storms, so having some defense boosting rainbow cards are very useful. High healing cards are also very useful with the corn. Above all this is the best deck because it has the most balance between heal and attack.

Blue Plains, Cornfields, Blue Plains, Corn Fields

As you may have noticed the deck used most throughout this guide is Corn Fields, that is because it is fairly simple to play and is based on attack. Blue Plains creatures are known for their strange floop abilities and strategic use, this deck is a combination of brute force and strategic thinking making it a good build for early and late game. Since the addition of the Blue Plains faction this deck is advised for experienced players.

Sandy Lands, Blue Plains, Nice Lands, Cornfields

This strategy is recommended for early players as it uses several different aspects of the game. The corn have high attack, the blue plains have various floops, the sandy lands have increase defense, and the nice lands have can heal themselves.

Useless Swamp, Cornfields, Cornfields, Blue Plains

This deck is recommended for players past the Ice Kingdom. This deck has a bit of a tank quality to it, with the corn raising attack and the useless swamp dealing damage. Recommended in this deck would be a Cornotaur or Legion of Earlings with the School House building. Given time, this combo will become nearly invincible to anything other than Cerebral Bloodstorms. Also, if you have Ancient Scholars, when something dies, you can go ahead and revive it. A Woadic Chief is also recommended for use with the Cornotaur, seeing that, when flooded repeatedly, it can dish out massive amounts of damage. This decks major weakness is the Cerebral Bloodstorm, so don't use this deck early on in the game.

Cornfields, Sandy Lands, Cornfields, Sandy Lands

A fairly popular choice of deck type giving a balance of attack based and defence based creatures, this deck is recommended for both new and experienced players. Use Sandy Lands for boosting your creatures defence at the same time you can combine this with using Corn Fields for boosting your creatures attack. If you have Sand Knight and Legion of Earlings you should try that deck. Combine these cards floops for the victory. If you are a begineer you should try this deck because you can easily craft Corn Dog, Archer Dan and Sand Snake. You can also loot or try cool chest for Beach Mums. These Nice rarity cards are very useful for begineers.

Sandy Lands, Nice Lands, Sandy Lands, Nice Lands

This might seem weird but it's a nice balance of healing based and defense based creature, this deck is recommended for both new and fairly experienced players. In this kind of deck you need to have creatures with high defense and an average attack, for example, my deck contains 3 beach mums, 4 fat goats, one travelin´wizard, and then you can include some sandy land cards with a fairly good attack such as a sandsnake or a sand jackal. You can balance the defense with the attack and the healing abilities using some spell cards. It's also a good idea to have high attack and high defense rainbow cards with similer floop abilites as the sandy lands and nice lands. You also need some good gold cards and a black card or two might also help. Having gold sanylands creatures can really boost up your deck, and some gold high level nicelands creatures can also help because of there tank-like defense. For example, I have a gold sand witch and a gold cotton saurus-rex. Also having a hero like Dr. Doughnut or Earl of lemon grab.